The present invention relates to fiberoptic devices and, more particularly, to a fiberoptic probe providing a concentrated generally circular pattern of light emission to one side of the tip.
In a number of medical procedures, it is necessary to deliver a concentrated pattern of light to one side of the probe to vaporize and/or coagulate tissue disposed to the side of the tip as it is moved within an organ or a blood vessel. One such procedure is in the treatment of benign prostate hyperplasia where the laser beam enlarges the passage through the prostate gland by vaporizing obstructing tissue.
Prior art devices for this purpose have been of two types:
In a first type, a plastic clad fiber has an angular surface polished on the tip so that the light reflected off the angular surface is projected as a large cone of light over the entire cylindrical surface on the side of the fiber. Much of this light hits the surface at an angle above the critical angle and is reflected back into the fiber to be scattered out of the fiber in the wrong direction. Only the light hitting the center of the cylindrical surface is above the critical angle and passes out of the side of the fiber in the desired direction.
In the second type, a glass clad optical fiber is provided with a relatively thick cladding, and the light is reflected off an angle polished surface and is reflected towards the outer cylindrical surface of the fiber. There is some internal reflection off the cylindrical surface formed by the core/cladding interface, and this light is scattered in the wrong direction. Since the difference in index of refraction between the core and cladding is relatively small, the amount of scatter is not very large and this can be an effective design. Because the cladding is relatively thick, a relatively small cone of light hits the cladding/air interface and gives no reflection. The disadvantage to this approach is that there will be some reflection off the core/cladding interface causing some scatter, and the cost of the glass clad fiber is much higher than the plastic clad fiber.
It is an object of the present invention to provide a novel fiberoptic probe which will emit light in a concentrated pattern at substantially a right angle to the axis of the fiberoptic probe.
It is also an object to provide such a fiberoptic probe which may be fabricated relatively readily and which is relatively long lived and reliable in operation.
Another object is to provide such a fiberoptic probe in which the pattern of light exiting therefrom may be manipulated by rotation and axial movement of the device.